/***************************************************************************
 *
 * Copyright (c) 2016 grab from kernel, Inc. All Rights Reserved
 *
 **************************************************************************/
/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  linux/include/linux/rbtree.h
  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...
  Some example of insert and search follows here. The search is a plain
  normal search over an ordered tree. The insert instead must be implemented
  in two steps: First, the code must insert the element in order as a red leaf
  in the tree, and then the support library function rb_insert_color() must
  be called. Such function will do the not trivial work to rebalance the
  rbtree, if necessary.
-----------------------------------------------------------------------
static inline struct page * rb_search_page_cache(struct inode * inode,
                         unsigned long offset)
{
    struct rb_node * n = inode->i_rb_page_cache.rb_node;
    struct page * page;
    while (n)
    {
        page = rb_entry(n, struct page, rb_page_cache);
        if (offset < page->offset)
            n = n->rb_left;
        else if (offset > page->offset)
            n = n->rb_right;
        else
            return page;
    }
    return NULL;
}
static inline struct page * __rb_insert_page_cache(struct inode * inode,
                           unsigned long offset,
                           struct rb_node * node)
{
    struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
    struct rb_node * parent = NULL;
    struct page * page;
    while (*p)
    {
        parent = *p;
        page = rb_entry(parent, struct page, rb_page_cache);
        if (offset < page->offset)
            p = &(*p)->rb_left;
        else if (offset > page->offset)
            p = &(*p)->rb_right;
        else
            return page;
    }
    rb_link_node(node, parent, p);
    return NULL;
}
static inline struct page * rb_insert_page_cache(struct inode * inode,
                         unsigned long offset,
                         struct rb_node * node)
{
    struct page * ret;
    if ((ret = __rb_insert_page_cache(inode, offset, node)))
        goto out;
    rb_insert_color(node, &inode->i_rb_page_cache);
 out:
    return ret;
}
-----------------------------------------------------------------------
*/

#ifndef _LINUX_RBTREE_H
#define _LINUX_RBTREE_H

#if defined(container_of)
#undef container_of
#define container_of(ptr, type, member)                    \
    ({                                                     \
        const __typeof(((type *)0)->member) *__mptr = (ptr); \
        (type *)((char *)__mptr - offsetof(type, member)); \
    })
#else
#define container_of(ptr, type, member)                    \
    ({                                                     \
        const __typeof(((type *)0)->member) *__mptr = (ptr); \
        (type *)((char *)__mptr - offsetof(type, member)); \
    })
#endif

#if defined(offsetof)
#undef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) & ((TYPE *)0)->MEMBER)
#else
#define offsetof(TYPE, MEMBER) ((size_t) & ((TYPE *)0)->MEMBER)
#endif

#undef NULL
#if defined(__cplusplus)
#define NULL 0
#else
#define NULL ((void *)0)
#endif

struct rb_node {
    unsigned long rb_parent_color;
#define RB_RED 0
#define RB_BLACK 1
    struct rb_node *rb_right;
    struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));
/* The alignment might seem pointless, but allegedly CRIS needs it */

struct rb_root {
    struct rb_node *rb_node;
};

#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3))
#define rb_color(r) ((r)->rb_parent_color & 1)
#define rb_is_red(r) (!rb_color(r))
#define rb_is_black(r) rb_color(r)
#define rb_set_red(r)               \
    do {                            \
        (r)->rb_parent_color &= ~1; \
    } while (0)
#define rb_set_black(r)            \
    do {                           \
        (r)->rb_parent_color |= 1; \
    } while (0)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) {
    rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
}
static inline void rb_set_color(struct rb_node *rb, int color) {
    rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
}

#define RB_ROOT \
    (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)

#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
#define RB_EMPTY_NODE(node) (rb_parent(node) == node)
#define RB_CLEAR_NODE(node) (rb_set_parent(node, node))

static inline void rb_init_node(struct rb_node *rb) {
    rb->rb_parent_color = 0;
    rb->rb_right = NULL;
    rb->rb_left = NULL;
    RB_CLEAR_NODE(rb);
}

extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);

typedef void (*rb_augment_f)(struct rb_node *node, void *data);

extern void rb_augment_insert(struct rb_node *node, rb_augment_f func,
                              void *data);
extern struct rb_node *rb_augment_erase_begin(struct rb_node *node);
extern void rb_augment_erase_end(struct rb_node *node, rb_augment_f func,
                                 void *data);

/* Find logical next and previous nodes in a tree */
extern struct rb_node *rb_next(const struct rb_node *);
extern struct rb_node *rb_prev(const struct rb_node *);
extern struct rb_node *rb_first(const struct rb_root *);
extern struct rb_node *rb_last(const struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
                            struct rb_root *root);

static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
                                struct rb_node **rb_link) {
    node->rb_parent_color = (unsigned long)parent;
    node->rb_left = node->rb_right = NULL;

    *rb_link = node;
}

#endif /* _LINUX_RBTREE_H */